This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my applications entitled APPARATUS AND METHOD FOR PREVENTING POOR OPERATION OF KEY DUE TO CHATTERING NOISE filed in the Korean Industrial Property Office on 27th of May 1997 and there duly assigned Serial No. P97-20949 by that Office.
1. Technical Field
The present invention relates to an apparatus and method for preventing poor operation of a key due to chattering noise, and specifically, to an apparatus and method for preventing poor operation of a key due to chattering noise. In that regard, xe2x80x9cchattering noisexe2x80x9d is the repeated opening and closing of contact points of tactile switches of a control button section attached to a display monitor because of external causes.
2. Related Art
Electric and electronic products generally employ microcomputers to control their additional devices. The microcomputer is also used to control a display monitor of a computer and each of its circuit blocks.
In particular, the microcomputer with a display monitor receives horizontal and vertical synchronous signals from the computer associated with the display monitor, and drives corresponding horizontal and vertical deflection circuits, as well as a high voltage circuit, to generate the necessary voltages for control of the display on a cathode ray tube (CRT) contained within the display monitor.
In addition, the display monitor typically includes a control button section containing switches for controlling (for example) horizontal position, vertical position, horizontal size, etc., of the image displayed on the CRT of the display monitor. Moreover, such a control button section often employs tactile switches which employ a contact point method. A problem arises in that, when a user employs the tactile switches, they can generate a chattering noise representing instability of the contact point due to physical and electrical causes externally created. This presents a problem to the operation of the display monitor, and therefore there is a need for the development of an apparatus and method for preventing poor operation of a key resulting from poor operation of a tactile switch of a control button section of a display monitor due to chattering noise generated in the tactile switch.
An object of the present invention is to provide an apparatus and method for preventing poor operation of a key due to poor operation of a tactile switch of a control button section of a display monitor as a result of chattering noise generated in the tactile switch.
To accomplish the object of the present invention, there is provided an apparatus for preventing poor operation of a key due to chattering noise, including: a control button section for generating a key signal to control a display monitor; and a microcomputer which contains a control program for preventing poor operation of a key due to chattering noise in the key signal generated by the control button section, by detecting the key signal when the chattering noise is generated, determining if the key signal is in a normal state or not, and processing the key signal.
A method of preventing poor operation of a key due to chattering noise according to the present invention includes the steps of: (a) detecting a key input voltage with an AD port of a microcomputer; (b) determining whether the key input voltage detected in step (a) is within the limits of a minimum and maximum voltage required for an effective key; (c) setting a key flag when it is determined that the key input voltage is within the limit required for an effective key; (d) resetting the key flag when it if determined that the key input voltage is not within the limit required for an effective key; (e) confirming the key flag setting from steps (c) and (d); (f) executing a key input according to a key execution voltage when step (e) confirms that the key flag is set; and (g) ignoring the key input when step (e) confirms that the key flag is not set.